1. Technical Field
The present invention relates to a method and apparatus for copper contamination control on in-line probe instruments typically used in integrated circuit fabrication and like processes.
2. Description of Related Art
A present trend in the integrated circuit fabrication industry is a move away from aluminum and towards copper damascene interconnect processes. A collateral problem raised by the increased use of copper in such applications is the potential for copper contamination during various phases of the chip fabrication in light of copper's diffusivity in silicon. If copper contamination finds its way to the active areas of the silicon on an integrated circuit package, the silicon can easily lose its critical effective properties, such as design capacitance at a specific contaminated site.
The potential for copper contamination raises a host of technical and logistical issue for an integrated circuit fabricator. For example, many metrology tools are used throughout the fabrication process. Typically, the availability of these metrology tools creates a bottleneck at the testing steps of the fabrication process. As integrated circuit fabricators transition from aluminum to copper technologies, cost considerations may require that the metrology tools used for the aluminum processes are also used for the copper processes. Yet, some of these tools require physical contact on a chip's metal layer during testing, resulting in residual metal contamination remaining on the tool after the test is complete. For example, electrical probe tips shows signs of copper contamination after being used on a copper wafer. This phenomena raises a concern of cross-contamination between sample pieces of copper to the substrate.
Accordingly, a need exists for copper contamination control on typical in-line probe instruments. The contamination control should include a method for quickly removing any copper contamination from the tip of the in-line probe instrument and further confirming the decontamination of the probe tip prior to continued testing.